T254 Mineralogy, Geochemistry, Petrology, and Volcanology Student Session (Posters)

Wednesday, 25 September 2024
8:00 AM - 5:30 PM
Hall D

LEAD ISOTOPE COMPOSITIONS OF CHEMICALLY SEPARATED SHALE COMPONENTS

Paper number: T254-9
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Due to their metal-rich and/or organic-rich nature, certain black shale units in the mid-continent US have been often linked to hydrocarbon occurrences and ore fields in the region. Shale is composed of inorganics, extractable organics (bitumen), and ‘non-extractable’ organics (kerogen). This work is an attempt to separate these three fractions from shales sampled from the mid-continent region and analyze the Pb isotope composition of each fraction. All the fractions of Pennsylvanian-age shales from the Forest City and Cherokee basins show relatively low radiogenic signatures. However, kerogen and/or inorganic components of certain shale units from the Ouachita mountains and the Ozarks are highly radiogenic (e.g. Chattanooga shale-inorganic: 206Pb/204Pb 34.00, Fayetteville shale-kerogen: 206Pb/204Pb 20.69, Womble shale-inorganic: 206Pb/204Pb 21.27), suggesting a potential genetic relationship with the Mississippi Valley-type (MVT) Pb-Zn ores. Overall, the bitumen component tends to be the least radiogenic of all three fractions (Ozark: 206Pb/204Pb: 18.34-18.77, Ouachita: 206Pb/204Pb 18.56-19.79, Pennsylvanian: 206Pb/204Pb 18.62-19.42). The Pb isotope compositions of the various fractions of the same rock are different, and the bulk-rock isotope composition is often not representative of all the fractions. Therefore, characterizing the various fractions is essential in evaluating potential rock units that contributed metals to the MVT ores.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-402409

© Copyright 2024 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.